The present invention relates to an infrared image pick-up apparatus for detecting a temperature of an object to be measured.
1. Field of the Invention
In picking up an infrared image by the use of an infrared image pick-up apparatus, it is necessary to make various adjusting operations of the apparatus during observation of an object.
2. Description of Related Art
Various kinds of portable type infrared image pick-up apparatuses are known. According to a typical construction, the operation thereof is performed by the left hand while holding an apparatus by the shoulder and the right hand. According to the apparatus, in the infrared image adjusting operation during observation, it is necessary to operate keys while watching alternatively a CRT (cathode ray tube) and an operation panel. According to another example, operation keys are mounted on the camera section which is separately provided from the processor and the operation keys are manipulated by one hand with the grip projecting from the center portion of the camera section held by the other hand. However, the construction is very inconvenient to operate. Furthermore, according to this construction, it is necessary to hold the processor on the shoulder in addition to the camera section, which creates a restraint in any adjusting operation of the infrared image.
On the other hand, infrared rays in accordance with an object are always emitted from the object having a temperature higher than absolute zero. Utilizing this, infrared rays emitted from the object are detected to measure the temperature of the object, which is already known. Additionally, an infrared image pick-up apparatus is widely known to pick-up such rays in two-dimension so as to form an infrared image.
In the apparatus, it is necessary to designate a criterion temperature for a first display, which is called "offset level", (the first display normally is a lowest temperature level) and a width of a temperature range being displayed, which is called "window", in displaying a temperature range on a screen thereof.
In known manners, such an offset level is adjusted so that an infrared image is displayed with suitable temperature distribution while observing the image displayed on a screen of the apparatus. However, it is difficult to adjust at a constant level because an infrared image itself has a high temperature part and a low temperature part which are mixed with each other. Specially, in a case where graduations of infrared images in the previous observation and the current observation are intentionally coincided to each other or a case where different objects to be measured are intentionally displayed in the same scale, it is difficult to adjust an offset level to set it into a constant value only by observing an infrared image.
Additionally, the above-described known adjustment of the offset level has another disadvantage: Change of gain in converting the intensity of an infrared image to the graduation of an infrared image causes the offset level to move at too high speed or too low speed. The latter requires a long time period to adjust the offset level.
Furthermore, in an infrared image pick-up apparatus for detecting an infrared ray emitted from an object to be measured and thus obtaining a video image indicating its temperature distribution, disclosed in, for example, Japanese Laid-open Patent Publication No. 62-19728, the peripheral temperature of the object to be measured greatly affects the measured result thereof. Therefore, the consideration of the influence is taken by measuring the internal temperature of the inside of the apparatus as already known.
However, the apparatus has several disadvantages: The apparatus requires large power consumption, so that the difference between the internal temperature and the peripheral temperature of the apparatus is about 10.degree. C. in a steady state. Furthermore, the apparatus has a large thermal capacity, so that it takes not less than one hour for the internal temperature to reach in a steady state. Additionally, it is necessary for measurement of an object with lower emissivity to correctly detect the peripheral temperature as well as the internal temperature of the apparatus for background correction.
On the other hand, the suitably usable temperature range of the apparatus is from -20.degree. C. to 50.degree. C., which is determined by the usable temperature range of electronic parts such as IC. If the apparatus is used other within the range, it is possible for the apparatus to cause failure. Therefore, it is necessary for a user to be informed of the possibility of the failure of the apparatus. Additionally, even though the apparatus is used within the range of -20.degree. C. to 50.degree. C. without the possibility of failure, when the apparatus is used other than a temperature range of 0.degree. C. to 40.degree. C., an error is caused in a measured temperature value in accordance with deterioration of the function of parts such as IC in the apparatus.
Accordingly, an essential object of the present invention is to remedy the above-described disadvantages in operations for adjusting an infrared image and to provide an infrared image pick-up apparatus capable of improving the operability in adjusting the infrared image.
Another important object of the present invention is to remedy such disadvantages in adjusting an offset level and to provide an infrared image pick-up apparatus capable of easily adjusting an offset level.
A further important object of the present invention is to remedy such disadvantages in correctly detecting a temperature of an object to be measured and to provide an infrared image pick-up apparatus capable of correctly estimating a peripheral temperature thereof by considering a power consumption amount thereof in estimating the peripheral temperature from an internal temperature, thereof utilizing that the peripheral temperature depends on the internal temperature, power consumption, and operating time of the apparatus, and thus detecting a temperature of an object to be measured.
A still further object of the present invention is to remedy such disadvantages in measuring a temperature of an object to be measured and to provide an infrared image pick-up apparatus capable of expressing a plurality of stages of warning displays such as a warning display when a peripheral temperature causes an error in a measured value in accordance with deterioration of functions of the apparatus and parts thereof and a warning display when a peripheral temperature causes possibility of failure of the apparatus and parts thereof, by always monitoring a peripheral temperature of the apparatus.